* {margin: 0; padding: 0;}
html{
    position: relative;
}
#main {/*多栏布局 https://www.css88.com/book/css/*/
    /*-webkit-column-width: 200px;*/
    column-count: 1;
}
@media (min-width: 400px) {
    #main {
        column-count: 3;
    }
}
@media (min-width: 1200px) {
    #main {
        column-count: 5;
    }
}
.box { /*每个图片之间的距离*/
    padding: 15px 0 0 15px;
    box-sizing: border-box;
}
.pic {
    padding: 15px;
    border: 1px solid #ccc;
    box-shadow: 0 0 5px #ccc;
    border-radius: 5px;
}
.pic img { /*所有图片等宽不等高*/
    width: 100%;
    heigth: auto
}